The War that Saved My Life by Kimberly Brubaker Bradley

The day got worse. It was bound to. The train stopped and started and stopped
again. Hot sun poured through the windows until the air seemed to curdle.
Small children cried. Bigger ones fought.
Finally we stopped at a quay, but a bossy woman standing there wouldn’t
let us out. She argued with the head teacher, and then with all the other
teachers, and then even with the man running the train. The teachers said we
had to be let out, for the love of mercy, but the woman, who had a face like
iron and a uniform like a soldier’s, only with a skirt, thumped her clipboard
and refused.
“I’m to expect seventy mothers with infant children,” she said. “Not two
hundred schoolchildren. It says so, here.”
“I don’t care in the least what’s written on your paper,” the head teacher
spat back.
The teacher supervising our car shook her head and opened the door. “Out,
all of you,” she said to us. “Loos are in the station. We’ll find you something
to drink and eat. Out you go.”
Out we went, in a thundering herd. The other teachers followed, opening
the doors to their cars. The iron-faced woman scowled and barked orders
everyone ignored.
It was more noise and rush than I’d ever seen. It was better than fireworks.
Jamie helped me off the train. I felt stiff all over, and I had to go something
desperate. “Show me how to use the loo,” I told him. Sounds funny, but it was
my first real loo. At home our flat shared the one down the hall, but I just
used a bucket and Mam or Jamie emptied it.
“I think I gotta use the boys’ one,” Jamie said.
“What do you mean, the boys’ one?”
“See?” He pointed at two doors. Sure enough, all the boys were going
through one door, the girls through another. Only now lines snaked out the
doors.
“Tell me what to do, then.”
“You pee in it, and then you flush,” he said.